Mr. OD-1 watched as Duffus got ready to launch his boat into the water. "It's gonna leak, Duffus" remarked OD-1.
"No, it shouldn't leak. I got in the boat, carefully patched all the holes with the patch kit recommended by the marina and then filled the boat with water to see if it would leak - and no leaks," replied Duffus.
"OK then, but you're gonna get wet," yelled Mr. Od-1 as Duffus launched the boat out into the lake, ignoring him. Moments later Duffus frantically rowed back to shore as the boat began to fill with water.
Why did Mr. Od-1 think that Duffus's repair would fail even though he used the proper repair materials?

Hint

Answer

Duffus patched the holes from the inside of the boat only. As he rowed out on the lake the water pressure forced the patch to come loose and the boat filled with water. This is much like putting you finger over the spout of a tap; the water pressure tries to force your finger away. If he had put a patch on the outside of the boat instead, the pressure would have forced the patch to stay in place, much like the plug in your sink.Hide